Quality Of Service In Ethernet Passive Optical Network Management

Nowadays, with the fast development of communication industry, backbone network and high speed LAN are updated continuously with increasing demand of bandwidth. However, the access network connecting backbone network and LAN becomes the bottleneck of the whole network. Current broadband access methods such as xDSL and HFC are widely used, but they can not provide sufficient bandwidth and QoS for new kinds of network services such as VOD, VOIP and so on. EPON system is a kind of passive optical network based on ethernet. EPON has become one of the best technologies in the next generation broadband access network because it has many virtues, such as easy to upgrade and operation, low cost and high bandwidth.Ethernet provides best effort service, which does not provide quality of service and equity for different users. The topology structure of EPON system contains many ONUs, which share bandwidth in the uplink direction using TDM method. So, bandwidth allocation scheme is very necessary for EPON system due to requests of higher uplink bandwidth utilization and QoS for different services.In the first part of this thesis, current situation of the access network and the technical of PON are introduced briefly. Then, the EPON system structure, OSI protocol model, especially the MPCP sublayer are introduced, the EPON control frame and data frame changed form ethernet frame are analyzed. After that, QoS management methods are introduced, including packet classification, congestion control and buffer queue management. Several queuing principles are compared such as FIFO queuing, prioritized queuing and weighted fair queuing. Tail drop and active queue management are also introduced in this part.In the next part of this thesis, the existing bandwidth allocation algorithms are discussed in detail at first, including static bandwidth allocation algorithm and dynamic bandwidth allocation algorithm. Then a new fixed cycle polling dynamic bandwidth allocation algorithm is proposed to support QoS and improve bandwidth utilization in EPON. The proposed algorithm consists of two parts: one is scheduling between OLT and ONUs, and the other is scheduling between priority queues in ONU. Simulation...